CHINESE JOURNAL OF MECHANICAL ENGINEERING Vol. 28,aNo. 3,a2015 ·511· DOI: 10.3901/CJME.2015.0228.020, available online at www.springerlink.com; www.cjmenet.com; www.cjme.com.cn Analysis of Thermoelastohydrodynamic Performance of Journal Misaligned Engine Main Bearings BI Fengrong * , SHAO Kang, LIU Changwen, WANG Xia, and ZHANG Jian State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China Received March 13, 2014; revised February 17, 2015; accepted February 28, 2015 Abstract: To understand the engine main bearings’ working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine main bearings are rarely considered simultaneously in most studies. A typical finite element model is selected and the effect of thermoelastohydrodynamic(TEHD) reaction on engine main bearings is investigated. The calculated method of main bearing’s thermal hydrodynamic reaction and journal misalignment effect is finite difference method, and its deformation reaction is calculated by using finite element method. The oil film pressure is solved numerically with Reynolds boundary conditions when various bearing characteristics are calculated. The whole model considers a temperature-pressure-viscosity relationship for the lubricant, surface roughness effect, and also an angular misalignment between the journal and the bearing. Numerical simulations of operation of a typical I6 diesel engine main bearing is conducted and importance of several contributing factors in mixed lubrication is discussed. The performance characteristics of journal misaligned main bearings under elastohydrodynamic(EHD) and TEHD loads of an I6 diesel engine are received, and then the journal center orbit movement, minimum oil film thickness and maximum oil film pressure of main bearings are estimated over a wide range of engine operation. The model is verified through the comparison with other present models. The TEHD performance of engine main bearings with various effects under the influences of journal misalignment is revealed, this is helpful to understand EHD and TEHD effect of misaligned engine main bearings. Keywords: main bearings, journal misaligned, oil film pressure, Reynolds equation, finite difference methods, thermoelastohydrodynamic(TEHD) 1 Introduction Nowadays there are more requirements for internal combustion engines with high performance and reliability to improve the journal bearings performance. With the trends in automotive industry, such as higher peak cylinder pressure, lower fuel consumption, engine downsizing and lower level of emission, all these tasks have been becoming a great challenge in the development of engine main bearings’ performances. In recent years, computer simulations have gained an increasing role in more complex simulation of technical problems even for bigger calculation domains with the increase of computer power. It is utmost necessary for research on the lubricant of main bearing for internal combustion engine. Traditional static linear finite element modeling techniques are not able to capture the nonlinearities and complex interactions among components * Corresponding author. E-mail: [email protected] Supported by National Science and Technology Support Program of China: Vibration and Noise Reduction Technology Research and Application of Bulldozers and Other Earth Moving Machinery(Grant No. 2015BAF07B04) © Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2015 specific to internal combustion engines [1] . Several investigations have focused on the analysis of dynamically loaded journal bearing with the purpose of emphasizing its operating properties and performance characteristics [2] . VORST, et al [3] , used the finite-length impedance bearing theory to model the steady-state behavior of flexible rotor-dynamic systems bearings. OSMAN, et al [4] , presented a numerical study of the performance of a dynamically loaded finite journal plastic bearing lubricated with a non-Newtonian of the bearing. The Reynolds equation was solved numerically, considering three values of the flow-behavior index and a wide range of journal speeds, materials and clearance ratios. MA, et al [5] , investigated the behavior of dynamically loaded journal bearings lubricated with non-Newtonian couple stress fluids. And the film pressure was solved numerically with Reynolds boundary conditions and the various bearing characteristics were calculated. MONTAZERSADGH, et al [6] , studied first dynamic load analysis of the crankshaft investigated. Finite element analysis was performed to obtain the variation of stress magnitude at critical locations while a dynamic simulation was conducted on a crankshaft. TANG [7] used a finite element method based on rectangular isoparametric element for evaluating the stiffness and
Analysis of Thermoelastohydrodynamic Performance of Journal Misaligned Engine Main Bearings
Jul 01, 2023
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